<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  手机号码：<input type="number">
  <button>发送</button>
  <script>
    var btn = document.querySelector('button');
    btn.addEventListener('click', function () {
      var time = 60;    // 定义剩下的秒数
      btn.disabled = true;
      btn.innerHTML = '还剩下' + time-- + '秒';
      var timer = setInterval(function () {
        if (time == 0) {
          clearInterval(timer);
          btn.disabled = false;
          btn.innerHTML = '发送';
        } else {
          btn.innerHTML = '还剩下' + time-- + '秒';
        }
      }, 1000);
    });
  </script>
</body>
</html>